Ignore the ignorant banter in the following video, and watch the fights closely.
In both situations, the non-aggressors made the same error. The allowed the aggressor to get too close to them.
The first man didn't even see the headbutt coming, but come it did. Headbutts are devastating strikes, using one of the the hardest parts of the body. Sure, they are uncomfortable to throw, but a properly placed headbutt, like we saw in the video are good for a very quick brutal KO.
The second fight was started when a Good Samaritan attempted to help the fallen man up. He lost awareness of his surroundings, and allowed the aggressive man to get too close. When engaged, the man did a good job of spinning to face his aggressor, but did a very poor job of escaping the front head lock.
The only reason he got out of the front headlock was because the aggressor let him out. If the aggressor wanted to throw some knees, take the man down, or try to work a neck crank, he was free to do so. Not a good situation to be in.
How do you avoid headbutts? Keep your aggressor at least at arm's length at all times. Be aware of your surroundings and do not get in to a face to face screaming match.
At arm's length, you have time to react to the aggressor. You can sprawl to avoid a take down, you can bring your hands up to block shots and you are in a good position to throw jabs to keep the aggressor away and set up bigger shots. Space is essential!
When helping out a downed person, you must be aware of what is going on around you. You can't just assume that no one will bother you simply because you are rendering aid. In fact, as in this situation, rendering aid makes you an automatic target for the aggressor, or a friend of the aggressor who sees an easy target of a "friend" of the fallen.
You are vulnerable, and carry no badge of athority, therefore you are free game. Be very careful.
How do you escape a front headlock? Easy. Watch:
Johnny Hendricks show this from the mat, but the moves are exactly the same from the standing position: Take control of the arm, non trapped arm goes out to the side, pull, and, shuck the rest of the body.
I like this movement much better than some of the other movements because I am moving toward my opponent's back, not giving my back up to my opponent.
You can see here:
Pablo Popovitch shows the extra detail of moving backwards to never allow your opponent to get set. The same thing when dealing with the standing front headlock.
Now, I feel VERY comfortable on the ground. If I am put in this same situation, I will most likely go to this ground position by simply moving backward and down until my knees touch the ground. My opponent will feel more and more in control as he puts more and more of his weight on top of my back. This is a good thing.
I is good for me, because by moving backward, I take away his ability to throw knees at the delicate areas of my face, the eye and nose bones. If he decides to throw knees he will only hit the very hard top of my skull. It won't feel good, but it won't break anything. Also, stretched out, if he throws knees it disrupts his base, making this arm drag escape that much more effective.
What about the back headlock? Even easier!!
The back headlock is one of the simplest moves to defeat. You are overbalanced to the front, and you are giving up your back. A simple change of balance and you are in a horrible position.
If you stay calm, and think, you will be able to easily escape these two situations. The front headlock is harder to escape from, but, with a little practice, you should be able to quickly master the technique.